Separating means and method

ABSTRACT

A METHOD AND APPARATUS ARE DISCLOSED FOR SEPARATING THE UNLIKE COMPONENTS OF A FLUID MIXTURE OF UNLIKE MATERIALS BY CONTACTING THE MIXTURE WITH SURFACE MEANS, PROVIDING RELATIVE MOTION BETWEEN THE MIXTURE AND THE SURFACE MEANS, WHICH MOTION EXERTS A FORCE ON THE MIXTURE PARALLEL TO THE SURFACE MEANS, THUS FORMING LAYERS OR ZONES HAVING A REDUCED CONCENTRATION OF AT LEAST ONE MATERIAL COMPONENT OF THE FLUID MIXTURE. AT LEAST A PART   OF ONE SUCH LAYER OR ZONE IS THEREAFTER REMOVED FROM THE MIXTURE.

A. a. HUNTER 3,705,099

SEPARATING MEANS AND METHOD Dec. 5, 1972 Filed May 18, 1970 I5 Sheets-Sheet I W 5* a; m W

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SEPARATING MEANS AND METHOD Filed May 18, 1970 3 Sheets-Sheet I Inventor ALLEN BRUCE HUNTER by: uwmtorney Dec. 5, 1972 Filed May 1 1970 A. B. HUNTER S'EPARATING MEANS AND METHOD 5 Sheets-Sheet 5 ALLEN BRUCE HUNTER by: gZ MAHomey United States Patent Ofice:

3,705,099 Patented Dec. 5, 1972 3,705,099 SEPARATING MEANS AND METHOD Allen Bruce Hunter, Dollard des Ormeaux, Quebec, Canada, assignor to Environmental Purification Systems,

Inc., Marblehead, Mass.

Filed May 18, 1970, Ser. No. 38,171 Claims priority, application British Provisional, June 16, 1969, 30,312 Int. Cl. B01d 43/00 U.S. Cl. 210-65 14 Claims ABSTRACT OF THE DISCLOSURE A method and apparatus are disclosed for separating the unlike components of a fluid mixture of unlike materials by contacting the mixture with surface means, providing relative motion between the mixture and the surface means, which motion exerts a force on the mixture parallel to the surface means, thus forming layers or zones having a reduced concentration of at least one material component of the fluid mixture. At least a part of one such layer or zone is thereafter removed from the mixture.

CHARACTERIZATION OF INVENTION The invention may be characterized as a method of separating the unlike components of an incoming fluid mixture comprising: Contacting the fluid with surface means; exerting a force on the fluid mixture by providing relative motion between the fluid mixture and the surface means, said force being exerted in a direction parallel to the surface means, thereby creating layers of fluid mixture of differing concentrations; and removing from the mixture at least a portion of one or more of such layers.

The invention may be further characterized in terms of an apparatus for separating an incoming fluid mixture of different materials, comprising essentialy: Surface means in contact with the fluid mixture for exerting a force on the mixture by providing relative motion between the mixture and the surface means, said force being parallel to the direction of motion of the surface means, thereby creating layers of mixtures having differing concentrations; and further means for removing from the mixture at least one layer of said mixture.

FIELD OF INVENTION This invention relatessto a method and apparatus for separating the unlike components of a fluid mixture and.

BACK-GROUND OF INVENTION The separation of particulate/fluid mixtures is being practised by diverse types of apparatus. Illustrative of prior art apparatuses and techniques are sedimentation, flotation, filtration, and devices utilizing centrifugal force. Such apparatuses and the techniques so employed have had indifferent results with many particulate/fluid mixtures.

Sedimentation and flotation devices rely respectively upon the settling velocity and buoyancy of the particulates in the fluid matrix. Centrifugal separators, where the primary force employed is inertial, are dependent upon density differences between the particulates and the fluid. As sedimentation, flotation, and centrifugal devices all depend on density differences between the materials to be separated they become less eflicient as the difference in density decreases. The interstices of filters may clog with particulates and may require periodic cleaning and replacement.

SUMMARY OF INVENTION It is an object of this invention to provide a method and apparatus to effect separation of particulate/fluid mixtures.

It is a further object of this invention to provide such method and apparatus which are particularly applicable to a continuous process.

It is still a further object to provide such a method and apparatus for the separation of fluid mixtures wherein the density of the particulates is substantially equal to the density of the fluid.

Yet another object is the provision of a method and apparatus having particular applicability to the removal of fibrous particles from fluid suspensions and to the enrichment of liquid/particle suspensions.

When a fluid stream flows past a solid surface in contact with it, such as a stationary body about which the fluid flows, or the walls of a conduit through which the fluid flows, a velocity gradient exists in the region near the surface. Fluid molecules in contact with the surface will have the velocity of the surface, that is zero velocity in the case of a stationary surface.

In the most usual practical cases of fluid flow, where the fluid flow is said to be turbulent, fluid not far removed from the surface has the velocity of the free flowing fluid. The fluid layers in between the fluid molecules in contact with the surface, and the free flowing fluid have intermediate velocities, due to the effects of forces of fluid friction which act in a direction parallel to the surface.

Also, observations of particulate/fluid mixtures flowing in conduits, show that the particulates tend to concentrate in the free flowing fluid; i.e., they leave the fluid layers between the wall and the free flowing fluid less concentrated in particulates than the free flowing fluid. These layers of fluid which are less concentrated in particulate matter than the free flowing fluid are herein referred to as the clean layer.

It has long been known among skilled researchers in the paper industry that when dilute suspensions of wood fibres in water flow past a solid surface, as in the case of white water flowing in a pipe line, fibres tend to gather in the bulk of the pipe, leaving a relatively fibrefree layer of water adjacent to the solid surface, i.e., an annulus of relatively fibre-free water forms along the pipe wall. This is a specific case of the clean layer. It is further known that in response to the forces of fluid friction, acting parallel to the surface, the relatively fibrefree clean layer adjacent to the surface flows more slowly than the more concentrated suspension of fibres somewhat more distant from the surface. In the pipe line, the relatively fibre-free annulus flows more slowly than the more concentrated suspension of fibres in the bulk of the pipe. It may be noted here that the wood fibres comprising the solid particulates of paper mill white Water have densities very nearly identical with that of water.

The present invention constitutes the conceptual recognition of these known physical phenomena and adapts them for a practical purpose, namely the formulation and construction respectively of unique methods and apparatus for (a) effecting concentration gradients in particulate/ fluid mixtures and (b) separating various concentrations from one another.

When a velocity differential exists between a surface and a particulate/fluid mixture in contact with it, forces parallel to the surface form a clean layer at the surface. The relative velocity necessary to generate the clean layer is far less than the velocities ordinarily employed in inertial separators, such as centrifugal separators, liquid cyclones, and the like. Also, the forces necessary to form the clean layer are much less than the inertial forces ordinarily employed in centrifugal separators, liquid cyclones, and the like. Furthermore, the forces which generate the clean layer act parallel to the surface, and thus generally parallel to the direction of relative motion, rather than transverse to the direction of motion as in the common types of inertial devices, including liquid cyclones.

Relative motion between a fluid mixture and a surface can be effected by causing a surface to move while in contact with a generally stationary body of fluid mixture, and a clean layer will be generated adjacent to the moving surface. The fluid molecules in actual contact with the moving surface will have velocities substantially equal to that of the surface, and a velocity gradient will exist between fluid layers adjacent thereto, due to fluid friction forces. Thus, although the body of fluid is generally stationary, localized fluid motion will be generated adjacent to the surface, in the direction of motion of the surface. Therefore the clean layer forms adjacent to the moving surface, and at least a portion of it moves in the direction of motion of the surface.

If a generally stationary body of fluid/ particulate mixture is contained within a vessel, the localized fluid motion travelling with and adjacent to a moving surface may generate an opposing pressure differential. This pressure differential may in turn generate further localized fluid motion further from the said surface in a direction opposite to that of the moving surface. Thus, within the generally stationary body of fluid contained within the vessel, two different localized fluid motions will have been introduced. The first travelling adjacent to and in the same direction as the moving surface, which generates a pressure differential along the path of motion, and a second localized fluid motion, further from the moving surface, in a direction opposite to the direction of motion of the surface. The localized fluid motion is the first direction, which includes at least part of the clean layer, will be a fluid mixture portion which is less concentrated in particulates than the main body of the fluid/ particulate mixture. The counter flowing fluid, in the second direction, will be more concentrated in particulates-than the main body of the fluid/particulate mixture. By a suitable arrangement of outlets, the fluid flowing in the direction of motion of the surface (which is relatively free of particules), and the counter flowing fluid mixture portion (which is more concentrated in particulates), may be separately removed. Then by provision of a suitably arranged feed inlet, an apparatus suitable for a continuous process will result.

The invention is well adapted to removal of particulates from liquid suspensions employed in paper and pulp manufacturing processes. However, the invention is not limited to such processes: It has equal utility in the separation of diverse types of particulate/fluid mixtures.

DISCLOSURE OF PREFERRED EMBODIMENTS With the considerations and inventive objects herein set forth in view, and such others as may become apparent from consideration of this disclosure and specification, the present invention consists of the inventive concept comprised, embodied, embraced or included in any means, method, process product, construction, composition, arrangement or combination of parts, or new use or any of the foregoing which may, herein be exemplified in one or more specific embodiments of such concept, reference being bad to the accompanying drawings, in which:

FIG. 1 is a horizontal section, approximately on the line 1-1 of FIG. 2, of the preferred embodiments of the invention utilizing a plurality of fins in the form of discoid rings projecting from the rotating cylinder thereof.

FIG. 2 is a transverse vertical sectional elevation of the separator of FIG. 1, on the line 22 of FIG. 1.

FIG. 3 is an enlarged fragmentary representation of a portion of the separator of FIGS. 1 and 2 on the line 3-3 of FIG. 2.

FIG. 4 is a transverse cross-sectional representation of a second modification of the inventive concept in the form of a separator having a small diameter shaft upon which large diameter centrally apertured discs are mounted.

FIG. 5 is a front elevation partly in section of a third modification of the inventive concept in the form of a separator employing relatively narrow concentric cylinders mounted upon a rotating disc taken on the'line 5-5 of FIG. 6.

FIG. 6 is a sectional elevation on the line 66 of FIG. 5.

FIG. 7 is a longtiudinal central cross-section of a fourth modification of the inventive concept in the form of a hollow cylindrical separator, on the line 77 of FIG. 8.

FIG. 8 is substantially a section on the line 88 of FIG. 7.

FIG. 9 is a plan view of a fifth modification of the inventive concept in the form of a longitudinally moving wall separator employing moving belts, and

FIG. 10 is a sectional elevation on the line 1010 of FIG. 9.

In the drawings, like characters of reference designate similar parts in the several figures.

PRELIMINARY DESCRIPTION To impart greater correspondence in this specification between the terminology of the diclosure and the claims thereof, the invention is a method of separating an incoming flow A (FIG. 1) of a fluid mixture B (FIG. 4) of unlike material characterized conceptually by the inventive method steps of contacting fluid mixture B with surface means C, exerting a force D- on the mixture B by providing relative motion as well depicted schematically in FIGS. 2 and 3, said force being exerted in a direction parallel to surface means C, thereby creating layers E of differing concentrations, and removing'from the mixture at least a portion of one or more of said layers. Such method may also include the step of removing the fluid layer adhering to the surface means, directly from the surface means as for example by such as the wipers F.

DETAILED DESCRIPTION Proceeding now to describe the invention with greater particularity wherein numerals may be substituted for those parts initially indicated by letters, a separator 10 (FIGS. 1 and 2) has a rotor 12 with its rotary axis horizontal, which rotor includes a large diameter cylinder 14 with a circumferential outer surface 16 and end walls 18. Mounted upon cylinder 14 are surface means C in the form of cylinder-encircling means or rings secured to and projecting from the cylindrical wall 19 of cylinder 14. In the separator 10 these rings are in the form of a plurality of equally closely spaced parallel discoid rings 20 rigidly attached to and projecting outwardly from said cylinder 14 for horizontal rotation therewith. Rings 20 have diametrically extending faces 22 and the exposed portions of the cylindrical circumferential outer surface 16 together with the plurality of faces 22 are collectively designated as surface 24.

Extending from end walls 18 is a pair of supporting stub shafts 26 coaxial with rotor 12 journalled in conventional bearings 28 which in turn are mounted upon a suitable frame structure not shown. One stub shaft 26 is connected to a source of power not shown by suitable means not shown to drive rotor 12 about is horizontal axis in a counterclockwise direction as shown in FIG. 2, as depicted by arrow 30.

The lower portion of rotor 12 is positioned within and surrounded on its lower side by a vessel 32 having portions 34 of approximately semi-circular cross-section which is concentric with and of slightly greater diameter than the outer rims 36 of discoid rings 20. The vessel 32 is closed at its ends by end sections 38-. The semi-circular or arcuate portions 34 of vessel 32 are interrupted by an enlargement or inlet trough 40 in open communication with the interior of vessel 32. At one end of vessel 32 trough section 40 communicates with an inlet pipe 43.

The upper edges 41 of arcuate portions 34 are extended by weir crests 42 and 44 respectively which weir crests are individually adjustable in vertical elevation by suitable means not shown.

Outlet flumes 46 and 48 are provided to carry away fluid flowing over weirs 42 and 44 respectively. The doctors or wipers 50 each composed of rubber or other flexible material supported by suitable rigid backing and 'stationarily mounted on suitable mounting means not shown are located between each pair of discoid rings 20 contacting the parallel surfaces of adjacent pairs of diametrically extending faces 22 and the portion of circumferential outer surface 16 between the discoid rings 20. Just beneath each wiper 50 is a trough finger 52 communicating with a collecting trough 54.

In operation, a particulate/liquid suspension 56 is introduced into vessel 32 through inlet pipe 43 and trough section 40 at a constant flow rate. As rotor 12 and attached discoid rings 20 are driven counterclockwise as shown in FIG. 2', through fluid mixture 56, sections of discoid rings 20 as shown in FIG. 3 move in the direction of arrows '58. Clean layers 60 are formed proximate to faces 22 as shown in FIG. 3 and also proximate to exposed cylinder surface 16. Due to fluid friction forces acting parallel to moving surface 24 (which includes faces 22) a localized fluid motion will occur in layers 62, moving in a first direction, the direction of motion of discoid rings 20, as depicted by arrows 64 in FIG. 3. As shown in FIG. 3 layers 62, moving in the first direction (that shown by arrows 64), will include at least a portion of clean layers 60.

The flow due to localized fluid motion caused by fluid friction in layers 62 causes the liquid surface 66 adjacent to weir crest 44 to be higher in vertical elevation than the liquid surface 68 adjacent to weir crest 42 (FIGS. 2 and 4). Thus there is a head differential or pressure differential between liquid surface 66 and liquid surface 68. This pressure differential, evidenced by the difference in vertical elevation between liquid surfaces 66 and 68 causes a counterflow of fluid, that is, a localized fluid motion in a second and opposite direction occurs between layers 62, as indicated by arrows 70 in FIG. 3.

Since layers 6'2 include at least portions of clean layers 60, differing concentrations of particulate matter will exist between layers 62 flowing in the first direction, and the fluid flowing in the second direction.

Careful observations of working models constructed generally according to the embodiment illustrated in FIGS. 1 and 2 indicate furthermore, that the counterflowing fluid, moving in the said second direction (per arrows 70), becomes more heavily concentrated along its path of travel. That is, the concentration of particulate matter in the localized flow in the second direction increases as this flow moves toward weir crest 42 as shown in FIG. 2.

Since liquid level 66 will be higher in elevation than liquid level 68, weir crest 44 should normally be adjusted higher in vertical elevation than weir crest 42.

By proper adjustment of the flow rate of incoming fluid 56 through pipe 43 and trough section 40, and adjustment of elevations of weir crests 42 and 44, fluid significantly lower in concentration of particulates than incoming fluid 56 flows over weir 44 and emerges through flume 48, while simultaneously fluid significantly higher in concentration of particulates than incoming fluid 56 flows over weir 42 and emerges through flume 46.

In the embodiment of FIGS. 1 and 2, an adhering layer of liquid remains on surface 24 and it emerges above liquid surface 66. This adhering layer of liquid is re- 6 moved by wipers 50, and falls from them into trough fingers 52 and thence to collecting trough 54 when it emerges through suitable outlet means such as a pipe not shown.

Since the adhering layer includes at least a part of clean layer 60 at the point of emergence from the liquid surface 66, liquid in collecting trough 54 is very significantly lower in particulate matter than incoming liquid 56.

Alternatively, trough fingers 52 and collecting trough 54 may be omitted. In this case, the adhering layer of liquid removed by wipers 50 falls back to liquid surface 66', whence it flows over weir crest 44 with a portion of layers 62 flowing in the first direction.

The separator embodiment 71 shown in FIG. 4 has a plurality of large diameter rigid centrally apertured discs or discoid rings 72 concentrically mounted on shaft 74 of much smaller diameter than cylinder '14 for rotation therewith in the direction of arrow 76. Shaft 74 is driven from a source of power not shown. The liquid level as depicted by broken line 78 is maintained well below the shaft. Discs 72 have diametrically extending faces 80 of relatively substantial superficial area. Faces 80 are parallel to each other on adjacent discs 72, the discs are relatively closely spaced, andare mounted with faces perpendicular to the axis of shaft 74.

The lower portion of discs 72 is partly surrounded by a shallow vessel including arcuate portions 82 terminating at their upper ends in outlet weirs 84 and 86 for eflluent flows which are respectively, more heavily concentrated in particulate matter and less heavily concentrated in particulate matter than the incoming fluid mixture which enters the vessel through inlet trough or inlet port 88. The radius of arcuate portions 82 is slightly greater than the radius of discs 72. In operation, a concentration gradient will be produced from weir 84 to weir 86.

Optionally, wiper means may be provided, as exemplied by wipers 90, capable of contacting the rotating surface means or diametrically extending faces 80. Wipers 90 remove the adhering layer of liquid from faces 80 after they emerge above liquid level 78. After removal by wipers 90, liquid from the adhering layer falls down, partly beyond weir 86, along with the efliuent flow over weir 86, and partly to the liquid level 78 proximate to weir 86.

The separator (FIGS. 5 and 6) has a disc 102 mounted on, and driven in a counterclockwise direction by shaft 104. A plurality of concentric cylinders 106 having primary cylindrical sulfaces 108 are mounted on disc 102 for rotation therewith. The disc 102 and cylinders 106 are partly immersed in a vessel 110 of semicircular cross-section, having feed inlet port 112 and a pair of outlets 114 and 116. The lower edges of outlets 1'14 and 116 are in the form of adjustable weirs 118 and 120 which may be adjusted in vertical elevation.

Wipers 122 suitably supported from end wall 124 by suitable means not shown are capable of contacting cylindrical surfaces 108. Wipers 122 are located in vertical elevation above outlet weir 120, which, in turn, is adjustably located in vertical elevation above outlet weir 118.

In operation, rotation of shaft 104 causes formation of clean layers in contact with primary surfaces 108, and a localized fluid flow in a first direction adjacent to each of surfaces 108 toward the outlet weir 120. Simultaneously, the pressure differential generated by the flow in the first direction, and maintained by the difference in vertical elevation between adjustable weirs 120 and 118 causes a flow in a second direction toward outlet weir 118. Thus a concentration gradient is formed along each arcuate fluid path defined by concentric pairs of cylindrical surfaces 108 from outlet weir 120 to outlet weir 118. Outlet 114 is for fluid having greater concentration of particulate matter, and outlet 116 is for fluid having lesser concentration of particulate matter than the incoming fluid mixture entering through inlet port 112.

A separator 13%, FIGS. 7 and 8 employs the inner cylindrical surface 132 of a rotating hollow cylinder 134, rotating counterclockwise about a horizontal axis as depicted by arrow 136 to form the clean layer. The outer surface of cylinder 134 is supported on, and driven by, a set of trunnion wheels 138 or by other suitable means. *In this embodiment, the cylinder 1% is itself the containing vessel for the fluid.

One end plate 140 of cylinder 134 is imperforate and rotates with it. The opposite end plate 142 is stationary, and sealed against the rotating cylinder 134 by rotary seal 114. Stationary end plate 142 supports inlet feed conduit 146, clean liquid outlet trough 148 and concentrated liquid outlet trough 150. A wiper 152, also supported from end plate 142 contacts the rotating inner cylindrical surface 132 above outlet trough 148.

In operation, a cylinder 134 rotates, fluid mixture containing particulate matter enters through inlet conduit 146, and a clean layer forms proximate to rotating inner cylindrical surface 132. As surface '132 emerges above fluid level 154, an adhering layer rises with it, and is removed by wiper 152, falling into clean liquid outlet trough 148. Since the adhering layer is composed at least in part of the clean layer formed proximate to surface 132 below fluid level 154, the emerging liquid leaving the cylinder through outlet trough 148 is less concentrated in particulate matter than the incoming fluid mixture. Concentrated liquid outlet trough 150 has one side in the form of a weir crest 156 over which liquid more concentrated in particulates than the incoming fluid flows.

A separator 160, FIGS. 9 and is shown in which the surface means C are continuous and is in the form of belt means specifically a plurality of continuous belts 162, supported and driven by pulleys 166 by drive means not shown. Facing surfaces 164 of adjacent belts 162 are driven in the same direction at the same speed. The belts are partly immersed in a rectangular vessel 168, having an inlet port 170 located in the bottom of the vessel and feeding an incoming fluid mixture containing particulate matter between the faces 164 which are parallel. The vessel has adjustable weir crests 172 and 174 located at the vessel end walls 175. Wiper blade pairs 176 and 178 are positioned adjacent to weir crests 172 and 174 respectively, bearing against the surfaces of belts 162 as they pass around pulleys 166 in such manner to prevent fluid flow between the belt passing around the pulley and the end walls of vessel 168. A lower belt edge seal 180 prevents fluid escape under the lower perimeters of belts 162. It will be noted that the portions of the belts 162 extending between pulleys 166 present faces 164 which are planar and that over a substantial path of travel the faces are parallel. In operation, clean layers are formed proximate to faces 164 which move in the direction depicted by arrows 182. Localized fluid flows in the first direction, which includes at least a portion of the clean layers, are formed due to fluid friction forces parallel with and adjacent to faces 164 moving in the direction depicted by arrows 184. A localized fluid flow in the second direction is caused by the pressure differential thereby generated, which flow moves in the direction depicted by arrows 186. Thus outlet weirs 172 and 174 are outlets respectively for fluid more concentrated in particulate matter than the incoming fluid mixture and fluid less concentrated in particulate matter than the incoming fluid mixture.

Various modifications may be constructed or performed within the scope of the inventive concept disclosed. Therefore what has been set forth is intended to illustrate such concept and is not for the purpose of limiting protection to any herein particularly described embodiment thereof.

What is claimed is:

1. A method of separating particles from liquid in a liquid mixture thereof when characterized by the combination of method steps of:

directing said mixture continuously into the space between essentially smooth surface means of substantial interfacing surface area relative to the volume of said mixture bounded by said area,

(a) providing relative motion between said mixture and said surface means whereby laminations of said liquid mixture having differing concentrations of particulates are formed,

(b) said laminations being approximately parallel with said surface means and having progressively less particulates therein the closer they are to the nearest portion of said surface means,

(c) said closer laminations being outer laminations,

(d) said laminations furthest from said surface means being inner laminations,

(e) the motion of said outer laminations being in the same direction as the motion of said surface means,

(f) the motion of said inner laminations being in the opposite direction to the motion of said surface means,

(iii) discharging into separate sinks (a) at least one of said outer laminations, (b) at least one of said inner laminations.

2. The method according to claim 1 in which said surface means rotate while at least partially submerged in said liquid mixture.

3. The method according to claim 2 in which said sinks are elongated and parallel with the rotary axis of said surface means.

4. The method according to claim 1 wherein said particulates are taken from the cellulosic group which includes wood pulp and bark fines.

5. Apparatus for the continuous separation of particulates from liquid in a liquid mixture thereof characterized in that said apparatus includes in combination:

interfacing generally parallel and essentially smooth surface means of substantial interfacing area relative to the volume of said mixture bounded by said area,

(a) means for providing relative motion between said mixture and said surface means whereby laminations of said liquid mixture having differing concentrations of particulates are formed,

(b) said laminations being approximately parallel with said surface means and having progressively less particulates therein the closer they are to the nearest portion of said surface means,

(c) said closer laminations being outer lamination,

(d) said laminations furthest from said surface means being inner laminations,

(e) the motion of said outer laminations being in the same direction as the motion of said surface means,

(f) the motion of said inner laminations being in the opposite direction to the motion of said surface means.

(iii) means for discharging into separate sinks:

(a) at least one of said outer laminations, (b) at least one of said inner laminations. 6. The invention according to claim 5 which includes a stationary vessel for incoming liquid mixture, said surface means being rotatable and partially submerged in said vessel.

" 7. The invention according to claim 6 in which said means for discharging being in the form of elongated passes parallel with the rotary axis of said surface means and either side of the vertical axial plane.

8. The invention according to claim wherein said particulates are taken from the cellulosic group which includes wood pulp and bark fines.

9 ,A method of separating particles from liquid in a liquid mixture thereof when characterized by the combination of method steps of:

directing said mixture continuously into the space between two or more adjacent and interfacing essentially smooth predominantly generally planar surface means of substantial interfacing surface area relative to the volume of said mixture, said surface area having a rotary axis lying substantially at right angles thereto,

(a) providing relative motion between said mixture and said surface means whereby laminations of said liquid mixture having differing concentrations of particulates are formed,

(-b) said laminations being approximately parallel with said surface means and having progressively less particulates therein the closer they are to the nearest portion of said surface means,

(c) said closer laminations being outer laminations,

(d) said laminations furthest from said surface means being inner laminations,

(e) the motion of said outer laminations bein in the same direction as the motion of said surface means,

(f) the motion of said inner laminations being in the opposite direction to the motion of said surface means,

(iii) discharging into separate sinks disposed upon either side of the vertical plane of said rotary axis:

(a) at least one of said outer laminations, (b) at least one of said inner laminations.

10. Apparatus for the continuous separation of particulates from liquid in a liquid mixture thereof characterized in that said apparatus includes in combination:

interfacing generally parallel and essentially smooth surface means of at least predominantly planar configuration and of substantial interfacing area relative to the volume of said mixture admissible between two adjacent surface means bounded by said area, said surface means being adapted for travel in the same direction,

(a) means for providing relative motion between said mixture and said surface means whereby laminations of said liquid mixture having differing concentrations of particulates are formed,

(b) said laminations being approximately parallel with said surface means and having progressively less particulates therein the closer they are to the nearest portion of said surface means,

(c) said closer laminations being outer laminations,

(d) said laminations furthest from said surface means being inner laminations,

(e) the motion of said outer laminations being in the same direction as the motion of said surface means,

(f) the motion of said inner laminations being in the opposite direction to the motion of said surface means,

(iii) means in the vicinity of the opposite extremities of travel of said surface means for discharging into separate sinks:

(a) at least one of said outer laminations,

(b) at least one of said inner laminations.

11. Apparatus for the continuous separation of particulates from liquid in a liquid mixture thereof characterized in that said apparatus includes in combination:

6) interfacing generally parallel and essentially smooth surface means of substantial interfacing area relative to the volume of said mixture admissible between two adjacent surface means bounded by said area, said surface means being:

' (a) rotatable and embodying in combination,

(b) a horizontal supporting cylinder and a plurality of circumferential rings having inner and outer perimeters thereon joined to said cylinder around said inner perimeters, said rings having opposite substantially parallel planar surfaces, said rings being spaced to permit said liquid mixture to flow therebetween,

(a) means for providing relative motion between said mixture and said surface means whereby laminations of said liquid mixture having differing concentrations of particulates are formed,

(b) said laminations being approximately parallel with said surface means and having progressively less particulates therein the closer they are to the nearest portion of said surface means,

(c) said closer laminations being outer laminations,

(d) said laminations furthest from said surface means being inner laminations,

(e) the motion of said outer laminations being in the same direction as the motion of said surface means,

(f) the motion of said inner laminations being in the opposite direction to the motion of said surface means,

(iii) means in the vicinity of the opposite extremities of travel of said surface means for discharging into separate sinks:

(a) at least one of said outer laminations, (b) at least one of said inner laminations. 12. The invention according to claim 11 which includes a stationary vessel for incoming liquid mixture, said surface means being rotatable and partially submerged in said vessel.

13. Apparatus for the continuous separation of particulates from liquid in a liquid mixture thereof characterized in that said apparatus includes in combination:

interfacing generally parallel and essentially smooth surface means of substantial interfacing area relative to the volume of said mixture admissible between two adjacent surface means bounded by said area, said surface means being:

(a) means for providing relative rotary motion between said mixture and said surface means whereby laminations of said liquid mixture having differing concentrations of particulates are formed,

11 (b) said laminations being approximately parallel with said surface means andhaving progressively less particulates therein the closer they are to the nearest portion of said surface means,

(ii) (a) means for providing relative motion between said mixture and said surface means whereby laminations of said liquid mixture having difz i closer lammatlons bemg outer ammafering concentrations of particulates are formed, b said laminations bein a roximatel arallel (d) sa1d lar-mna-uons fun-bestfrom sa1d surface zvith said surface means an d having prgggessivemeans being Inner. lammatlons. ly less particulates therein the closer they are to (e) the motion of said outer lamlnatrons being in the nearest portion of said surface means the same directlon as the motion of sa1d surface 10 (c) Said closer laminations being outer l'alfiinw means,

tlons (f) the motion of sa1d 1nner lamlnatlons being in 2 the opposite direction to the motion of said z fig 822 :323 352;3 5: sa1d Surface surface means (iii) (e) the motion of said outer laminations being in the same direction as the motion of said means in the form of elongated passes parallel with surface means,

the rotary axis ofvsaid surface means and upon either (f) the motion of said inner laminations being in side of. the vertical rotary axial plane thereof for the opposite direction to the motion of said discharging into separate sinks: surface means, '1

(a) at least one of said outer laminations, (iii) (b) at least one of said inner laminations, and a stationary vessel for incoming liquid mixture, said f g izggffg g g g a ggg? ig ig surface means being partially submerged in said vessel. (b) at; least one of Said inner lamination; 14. Apparatus for the continuous separation of particulates from liquid in a liquid mixture thereof charac- References Cited terized in that said apparatus includes in combination: UNITED STATES P TEN S (i) 2,943,946 7/1960 1 Hawtin et al. 210-512X interfacing generally parallel and essentially smooth 3 233 742 2 19 Shaines et 1 210433X surface means in the form of substantially hori- 3 3 350 zontally travelling and spaced belts rotatable about vertical axes, said belts presenting a substantial interfacing area relative to the volume of said mixture admissible into said interfacing area and bounded thereby,

8/1968 Kubat et a1. 2 10-322 FRANK A. SPEAR, JR., Primary Examiner US. Cl. X.R. 

